Illumination apparatus, e.g., desk lamps, floor lamps, wall lamps, are widely used by people when reading or working One major concern when using these illumination apparatus relates to the user's posture.
A desk lamp using ultrasonic sensors to detect a user's posture is disclosed in Chinese utility model CN2847008Y. The desk lamp comprises a head-detection circuit and a body-detection circuit, both equipped with an ultrasonic sensor capable of transmitting and receiving ultrasonic signals. The body-detection circuit is used to detect whether the user is sitting in front of the desk, and the head-detection circuit is used to detect whether the head of the user is below a preset horizontal plane. If the latter is the case, the head is below a preset alarm plane, meaning that the head cannot reflect the ultrasonic waves sent from the head-detection circuit back to the head-detection circuit, which will result in an alarm from an alarm circuit to remind the user to raise his/her head to get the right sitting posture. The proposed desk lamp is based on the assumption that a lower height of the head is equivalent to an improper sitting posture, and has the disadvantage that it generates a noticeable alarm signal which is probably disturbing to the user when he is working and which highly relies on the user's conscious response to the alarm signal.
There is always a need to correct people's posture when they are reading or working.